Tissue fusion/welder apparatus and method

ABSTRACT

A tissue welding apparatus is adapted to fuse a first piece of tissue to a second piece of tissue which are disposed in a surface proximate relationship. An elongate shaft carries a first jaw, and a second opposing jaw moveable relative to the first jaw. At least one penetrating member is carried by the first jaw and moveable relative to the second jaw to create a channel through the first piece of material and the second piece of material. A source of heat is coupled to the penetrating member for denaturing the tissue defining the channel. This denatured tissue forms a column binding the first piece of tissue to the second piece of tissue. A chemical agent can be carried to the tissue with the penetrating member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to surgical devices and, in particular,to an apparatus and method for fusing and/or welding tissue.

2. Discussion of Related Art

Surgery generally involves the cutting and fixing of tissue. The cuttingis usually undertaken in one of two modalities, either cold cutting orhot cutting. Cold cutting is performed using a mechanical device such asa knife or scissors. Hot cutting involves the use of high frequencyelectrosurgical current, ultrasonic sound or heat. The fixation of cuttissue commonly involves the use of sutures, staples or clips. Morerecently, tissue adhesives have evolved as an occasional alternative.

The process of inhibiting blood flow from cut or severed tissue,commonly referred to as hemostasis, is often undertaken using powergenerated by an electrosurgical device. Various electrosurgical effectscan be achieved, such as coagulation, fulguration and cauterization.Coagulation makes use of high frequency electrosurgical waveforms thatare designed to desiccate tissue by vaporizing the cellular content andthereby restricting the flow of blood from the site. Fulguration is aform of coagulation that is more broadly applied to provide hemostasisover large areas. Cauterization is a well-known form of hemostasis andhas been used for many years. A hot instrument applied to a portion ofthe severed or damaged tissue will normally arrest blood flow. Theapplication of heat to the tissue fuses the cellular content andactually welds cellular content in a manner somewhat similar to metalwelding.

Several procedures have evolved which use devices that provide bothcutting and fixation in a single instrument. The most common of thesedevices comprises a surgical stapler that places two rows of titaniumsurgical staples and subsequently cuts the tissue between the rows.These devices are often referred to as “take-down” devices. They areused to divide body passages and provide concomitant fluid stasis.

An example of such devices is the commonly available gastrointestinalanastamosis (GIA) type stapler. It comprises a jaw fitted with acartridge holding four to six rows of staples in a deployable position,a hinged anvil sized and configured to deform the staples of thecartridge, and a shaft communicating with a handle held by a user. Inuse, the device is placed along, and compressed upon, a portion oftissue to be cut and stapled. The staples are subsequently urged throughthe tissue and against the anvil where they are deformed into apreferred folded-over condition. A sharp surgical blade is then movedforward between rows of staples to divide the tissue. Fluid stasis isaccomplished by the overlapping rows of folded-over and compressedstaples.

As one would imagine, it is not desirable to over-compress tissue ordevelop a condition where required nourishment to tissue is compromised.If too many staples are placed or if the staples are over-compressed,the included tissue may be deprived of nutrition and may subsequentlynecrose and cause serious complications. In addition, staples aretypically formed of a material which is foreign to the body and maycause responses that will further complicate recovery or healing.Staples cannot be cut through or removed easily. Staples also causeproblems with imaging technologies. They may show up as artifacts inMRI, CT scans and fluoroscopy.

Surgical clips are often used to occlude small vessels. They normallycomprise a C-shaped metallic member that is highly compressed upontissue. Nourishment to the residual portion of “clipped-off” tissue iscompletely interrupted. Even when a divided or repaired portion oftissue is sutured, special care is taken not to place the suture tootightly so that nourishment to the residual portion is interrupted.

Tissue adhesives, which provide hemostasis as well as the “gluing” oftissue, have proven to be effective. However, they often require priorpreparation from autologous materials. In addition, they do not have thefull confidence of the medical community.

To avoid the complications of clips, staples, adhesives and sutures,attempts have been made to fuse or weld tissue. For instance, a vesselmay be clamped tightly with a hemostat or grasper, and subsequentlyenergized with an electrosurgical generator. This technique is commonlyreferred to as “buzzing the hemostat”. The heat generated within thetissue may cause the proteins of the cellular content to fuse and createa fluid-tight arrangement.

This technique has proved to be relatively effective in small vessels;however, large vessels are not indicated for this approach. Therelationship between the diameter of the vessel and the wall thicknesshas proven to be the limiting factor in tissue fusion and welding inmost cases. Hemostatic graspers are available that compress tissue andapply an electrosurgical discharge that mimics the energized hemostat.

An electrosurgical generator is to supply a high voltage at a highfrequency in order to produce an electric arc between an electrosurgicalinstrument and grounded tissue. This “electrosurgical effect” (ESE) isespecially suited to cut and coagulate tissue in a quick and effectivemanner. However, the ESE is not effective to divide and providehemostasis or fluid stasis in large vessels or conduits. While the ESEhas been well adapted to seal small capillaries, it has not beeneffective to shut-off the fluid flow in a large conduit.

SUMMARY OF THE INVENTION

In view of the foregoing, the present invention comprises a device, andassociated method, which is sized and configured to emulate themechanical fixation of tissue. The present invention provides permanentfluid stasis in tissue by creating small, discrete tissue welds along apreferred pathway, and subsequently cutting relative to the welds. Thewelding or fusing of the tissue is accomplished by application of heatto selected and localized areas. In a preferred embodiment, a deviceaccording to the present invention may comprise an elongate shaft havinga handle at the proximal end and a pair of jaws at the distal end. Thejaws comprise a first portion having a plurality of penetratingelectrodes or elements, and a second portion having an electricalcontact/compression member.

With the intent of merely heating the tissue adjacent the electrodes,the jaws can be connected in an electrosurgical monopolar, bipolar or“quasi” bipolar configuration. The electrodes can also be energized withdirect current or any other heating source, in order to achieve thedesired heating and consequent fusing or welding of tissue.

In one aspect of the invention, the device includes a first member and asecond member opposing the first member. The first member is sized andconfigured to push a plurality of needle electrodes or elements throughthe tissue, where they contact the second member thereby providingelectrical continuity. Upon application of electrical or thermal energy,the tissue through which the electrodes have passed is heated to thepoint of desiccation and subsequent fusion of certain cellularcomponents. The resulting fusion or weld is continuous through thelayers of tissue and resembles a “rivet”. A plurality of fusion“channels” arranged appropriately provides fluid stasis without theintroduction of any foreign material.

In other aspects of the invention, the jaws can be provided by ahemostat; a chemical-releasing sleeve may also be employed. A deviceaccording to the present invention overcomes the limitations of existingdevices by providing a multiple-use device as opposed to a single-fireor single-use device.

These and other features of the invention will become more apparent witha discussion of the various embodiments in reference to the associateddrawings.

DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included in and constitute a partof this specification, illustrate the embodiments of the invention and,together with the description, explain the features and principles ofthe invention. In the drawings:

FIG. 1 is a perspective view of a laparoscopic device according to thepresent invention;

FIG. 2 is a perspective view of the distal portion of a laparoscopicdevice according to the present invention, in a closed condition withthe tissue to be fused;

FIG. 3 is a perspective view of a portion of tissue that has been fusedby the device of the present invention;

FIG. 4 is a perspective view of a portion of tissue that has been fusedand divided by the device of the present invention;

FIG. 5A is a side elevation view of the distal portion of the deviceshowing the electrodes and connector in a closed condition;

FIG. 5B is a side elevation view of the distal portion of the deviceshowing the electrodes and connector in an open condition;

FIG. 5C is a side elevation view of the distal portion of the deviceshowing electrodes and connector in an open, and tissue-receivingcondition;

FIG. 5D is a side elevation view of the distal portion of the deviceshowing the electrodes and connector in a closed, tissue-engagingcondition;

FIG. 5E is a side elevation view of the distal portion of the presentinvention showing the electrodes and connector in an open,tissue-releasing condition;

FIG. 6A is an end elevation view of the distal portion of the deviceshown in FIG. 5A;

FIG. 6B is an end elevation view of the distal portion of the deviceshown in FIG. 5B;

FIG. 6C is an end elevation view of the distal portion of the deviceshown in FIG. 5C;

FIG. 6D is an end elevation view of the distal portion of the deviceshown in FIG. 5D;

FIG. 6E is an end elevation view of the distal portion of the deviceshown in FIG. 5E;

FIG. 7 is a top plan view of a portion of a body conduit that has beenfused using the present invention;

FIG. 8 is a top plan view of a portion of a body conduit that has beenfused and divided using the present invention;

FIG. 9 is a cross section view of the fused or welded body conduit,taken along lines 9-9 of FIG. 8.

FIG. 10 is an enlarged view of the cross section illustrated in FIG. 9;

FIG. 11 is a perspective view of a fusion area produced by an embodimentof the present invention;

FIG. 12 is a top plan view of the fusion area shown in FIG. 11;

FIG. 13 is a top plan view similar to FIG. 8 and illustrating anutritional pathway in a fused tissue portion;

FIG. 14 is a side elevation view of a distal jaw portion comprising adirect current power source;

FIG. 15 is a side elevation view of a distal jaw portion comprising abipolar electrosurgical power source;

FIG. 16 is a side elevation view of a distal jaw portion comprising a“quasi” bipolar electrosurgical power source;

FIG. 17 is a side elevation view of the distal jaw portion comprising adirect heat source;

FIG. 18 is a side elevation view of a chemical releasing embodimentadapted for bonding enhancement;

FIG. 19 is a side elevation view of a distal jaw portion configured withelectrodes on both opposed jaw portions;

FIG. 20 is a side elevation view of a distal jaw portion having amechanical cutting member;

FIG. 21 is a side elevation view of a distal jaw portion having anelectrosurgical cutting member;

FIG. 22 is a side elevation view of a distal jaw portion sized andconfigured to fit through a small-bore cannula;

FIG. 23 is a top plan schematic view of a solid-state electronicswitching arrangement for energizing the electrodes of a distal jawportion;

FIG. 24 is a top plan schematic view of a mechanical switchingarrangement for energizing the electrodes of a distal jaw portion;

FIG. 25 is a side elevation schematic view of a sequential mechanicalswitching arrangement for lifting and energizing the electrodes of adistal jaw portion;

FIG. 26 is a side elevation schematic view of a distal jaw portionhaving a permeable anvil;

FIG. 27 is a side elevation schematic view of a distal jaw portionhaving a sliding contact permeable anvil;

FIG. 28 is a side elevation view illustrating radio frequencyelectrosurgical cutting with a penetrating needle;

FIG. 29 is a side elevation view illustrating electrosurgical cuttingand heating of a penetrating needle;

FIG. 30 is a side elevation view illustrating the direct heating of thepenetrating needle;

FIG. 31 is a side elevation view of a hemostat having penetratingneedles and being configured for operation in a monopolarelectrosurgical configuration;

FIG. 32 is a side elevation view of a hemostat having penetratingneedles and being configured in a bipolar electrosurgical configuration;

FIG. 33 is a side elevation view of a hemostat having penetratingneedles and being configured in a direct heat configuration;

FIG. 34 is a side elevation view of a hemostat having penetratingneedles and being configured for use with an external heat source;

FIG. 35 is a perspective view of a further embodiment of the inventionhaving a chemical releasing sleeve;

FIG. 36 is a side elevation perspective view of a distal jaw portionarranged in a monopolar electrosurgical configuration;

FIG. 37 is a side elevation schematic view of a distal jaw portionarranged in a bipolar electrosurgical configuration;

FIG. 38 is a side elevation schematic view of a distal jaw portionarranged in a “quasi” bipolar electrosurgical configuration; and

FIG. 39 is a side elevation schematic view of a distal jaw portionarranged with a direct current, resistance-type configuration.

DESCRIPTION OF THE INVENTION

With reference to the drawings of FIGS. 1 and 2, a tissue welder 10 inone embodiment of the present invention is shown to include a handle 11,and an elongate shaft 14, and a distal portion 16. This distal portion16 includes a pair of opposing jaws 21 and 23 which are adapted tocompress tissue 18, having outer surfaces 19 that define deep innerportions 20.

In the illustrated example, the compressed tissue 18 has theconfiguration of a tube where one side of the tube is compressed into asurface proximate relationship with the other side of the tube in orderto occlude the tube. It will be appreciated that the invention isequally adapted to bond any two pieces of tissue disposed in a tissueproximate relationship.

One of the opposed jaws 21 is configured to have a plurality ofpenetrating members or needles 25. The opposite jaw 23 provides a stopor a contact member against which the penetrating members 25 can bemoved. Energy is delivered to, and through, the penetrating members 25in such a manner that the tissue 18 contacted by each penetrating member25 is deformed at a cellular level and fused or welded.

Operation of the tissue welder 10 can be best understood with referenceto the progressive side views of FIGS. 5A-5E and the associatedprogressive end views FIGS. 6A-6E, respectively.

More specifically, a portion of the tissue 18 is placed between theopposed jaws 21, 23 (FIGS. 5C and 6C) and lightly compressed (FIGS. 5Dand 6D). As the compression occurs, the sharp needles 25 are urgedthrough the compressed tissue 18 and into contact with, or in closeproximity to, the opposing jaw 23. In one embodiment, electrical currentis introduced through the needles 25. These needles 25 are made from anelectrically high resistance material so that the electrical currentproduces heat. It follows that the tissue 18 in contact with the needles25 is heated, preferably to a point where the cellular content isvaporized, and the protein components fused to form a contiguousstructure through the tissue 18 adjacent to the needles 25. When theneedles 25 are removed and the jaws opened (FIGS. 5E and 6E), aplurality of fused columns or channels remain with lumens whichrepresent needle entry and exit points. In this embodiment, the fusedcolumns are arranged in a pattern that is secure and fluid-flowarresting.

The pattern may include, for instance, a first group 27 of two or threeclosely spaced rows of fused columns, spaced apart from a second group30 of two or three closely spaced rows of fused columns as illustratedin FIG. 7. A cutting or dividing member 32, in the form of a blade or anelectrosurgical electrode, may be urged to divide the first group ofrows 27 from the second group of rows 30 so as to sever the tissue 18 ofthe conduit, as illustrated in FIG. 8. These divided portions 36, 38 areeach sealed in a fluid tight manner by the respective groups of fusedcolumns 27, 30.

It will be appreciated that there are at least three considerationswhich might be addressed in dividing a body passage such as an artery, avein or a portion of colon, intestine or bowel. A first consideration isthat of sealing the lumen so that the contents of the body passage arenot released in an uncontrolled manner. The second consideration is thatblood flow from an incision or cut be arrested or at least minimized. Athird consideration is that adequate nutrition can be maintained withinthe divided or residual portions 36, 38 of the affected tissue 18.

Referring to FIGS. 9-13, fused columns 41 associated with the presentinvention are seen in an arrangement that provides a secure connectionbetween the extreme tissue margins at intervals that permit nourishmentflow 42 to the residual portions 36, 38 (FIG. 13). A closer look at thefused-columns 41 reveals that denatured cellular components have beenfused or welded adjacent to the penetrating needles 25. The penetratingneedles 25 heat the adjacent tissue only in the immediate area aroundthe needles so that tissue further removed from the needles 25 remainsin a natural condition.

Generally, a larger area 43 of thermal modification exists at eachtissue surface 19, while a smaller area 45 of thermal modificationexists at the larger and deeper portions 20 of the tissue 18. Thisprovides the denatured column with an hourglass configuration. Thesealing of the lumen 41 in the embodiment, requires only that the tissuebe heated in proximity to the penetrating needles. For comparison, itwill be noted that devices of the prior art rely on a transfer ofthermal-energy through the entire portion of tissue indiscreetly. Oneadvantage of this embodiment is that thermal energy is localized inorder to maximize the health, vitality and perfusion of the remainingtissue.

Additional embodiments of the invention are illustrated in FIGS. 14-17.In these embodiments, the opposed jaws include the jaw 21 which has afixed relationship with the elongate shaft 14, and the jaw 23 which ishinged to the jaw 21 and moveable relative to the shaft 14. The firstjaw 21 may be sized and configured to receive a cartridge containing aplurality of the metallic penetrating needles 25 or electrodes. In theembodiment of FIG. 14, the needles 25 are in electrical continuity withone electrical pole of a direct-current power source 47. The second,movable jaw portion 23 is in electrical continuity with the oppositeelectrical pole of the same direct current power source 47. Thepenetrating needles 25, in the preferred embodiment, are made of a metalthat exhibits high electrical resistance. As electricity flows throughthe circuit made by contacting the needles of the first jaw 21 with thecontact surface of the second jaw 23, heat is generated within theneedles 25. It should be noted that all of the needles 25 need not beenergized simultaneously. In fact, sequential activation may bepreferred as it diminishes the amount of energy required at any one timefor the desired effect.

In the embodiment of FIG. 15, the tissue welder 10 is connected to anElectrosurgical Generator (ESG) 50. Most ESGs have a bipolar (BP)connection, a monopolar (MP) connection and a return-path (RP)connection. Coupling the welder 10 to the BP function of the ESGconnects one pole of a current flow path to the jaw 21, and connects anopposite pole of the current flow path to the jaw 23.

A monopolar connection involves a ground plate 52 as illustrated in FIG.16. In this embodiment, a high frequency, high voltage alternatingcurrent from the generator 50 flows between the poles and through thecontacting needles 25 of the first jaw. The current density existing inthe needles 25 causes them to become hot and fuse the tissue 18.

In the embodiment of FIG. 17, a heating element 54 is placed in contactwith the penetrating needles 25. The heating element 54 may heat all ofthe penetrating needles together or may heat them sequentially or ingroups such as rows. An electrical circuit or a mechanical motion mayfacilitate control of heat transfer to the penetrating needles. Theselection of individual needles 25 or groups of needles will allow theincluded tissue to cool down between applications of heat through thetissue. The tissue 18 surrounding the fused-columns 41 will remainpatent if it is not continuously exposed to the heat required to performthe fusion or tissue welding associated with the present invention.

With reference to FIG. 18, a surgical retractor is shown to include afirst tissue-penetrating member, such as the jaw 21, and a secondnon-penetrating member, such as the jaw 23. The independent first andsecond members may be used to mobilize or move tissue, and to hold it ina preferred position or condition. The second member 21 may,subsequently, be placed in position on the opposite side of the targettissue. When appropriately positioned, the first and second members maybe energized to create heat within the penetrating needles 25. Thepenetration sites form fused or welded columns through the targettissue.

An additional advantage of the present invention can be appreciated fromthe embodiment of FIG. 18 where a chemical releasing member 56 is placedupon each of the penetrating needles 25. As the needles 25 and theassociated chemical releasing members 56 are forced into the tissue, achemical 58 is drawn into the puncture sites. The chemical may include athrombogenic material, a fibrogenic material, a coagulant, germicidal,anti-microbial material, an adhesive, or a lubricant material, forexample. In a preferred embodiment, each of the chemical releasingmembers 56 contain a compressible foam that releases the chemical 58 asthe foam is compressed.

An alternate embodiment of the present invention is seen in FIG. 19where the first jaw 21 is fitted with a first group 60 of the tissuepenetrating needles 25, and the second jaw 23 is fitted with a secondgroup 61 of the tissue penetrating needles 25. The first group 60 of theneedles is arranged so that they do not interfere with a second group 61of the needles. This arrangement of the needles 25 leaves a pattern offused or welded lumens that is most appropriate for security andfluid-stasis, and that permits appropriate nutrition to the residualtissue.

Referring to FIGS. 20 and 21, a mechanical cutting member 63 can beemployed with the tissue fusing needles 25 of the present invention.After fusion or welding of the target tissue has occurred andappropriate fluid stasis is achieved, the mechanical cutting member 63can be advanced along an arrow 65 to divide the two fused or weldedportions of tissue. The cutting member 63 in the illustrated embodimentcomprises a sharpened surgical blade that is straight, curved or angled,and that can be advanced or retracted as required.

An additional embodiment may include an electrosurgical cuttingelectrode 64 (ESE), as shown in FIG. 21. The ESE may be a wire, a blade,or a snare that is independently connected to the ESG 50. In the case ofelectrosurgical cutting, an electrosurgical coagulation mode or ablended waveform may be chosen that coagulates small remaining bleeders.Thus, the electrosurgical effect may be achieved independently of theelectrode 64 with the heating of the penetrating needles 25. In anadditional embodiment, the electrosurgical voltage may be broken-down oradjusted to perform the heating of the penetrating needles 25 prior toactivation of the cutting electrode 64.

With reference to FIG. 22, particular attention is drawn to thepotential of different embodiments to be sized and configured for use in“small-bore” laparoscopy. Either or both of the opposed jaws 21,23, canbe fitted with the tissue penetrating needle group 60, 61, which can beenergized and subsequently heated to fuse or weld tissue as previouslydisclosed. The force required to occlude a body passage is generallyavailable in small-bore laparoscopic instruments. However, there isoften insufficient room in a small-bore instrument to facilitate eitherthe application or the formation of staples. The present inventionreplaces staples of the prior art, with electrical heating of specificregions of tissue to the point of cellular fusion.

The method and apparatus used to energize the electrodes in variousembodiments of the invention may differ significantly. For example, inFIG. 23, a solid-state electronic switching arrangement 65 isillustrated for selectively energizing the electrodes or needles 25. Theelectrodes can be individually and sequentially energized and of coursecan be energized all at once. As illustrated in FIG. 23, small groups ofthe electrodes can be energized simultaneously with different groupsbeing energized sequentially.

FIG. 24 illustrates a mechanical switching arrangement wherein anenergizing block 67 is moved among the electrodes or needles 25 toactivate those needles in contact with the block 67. In such anembodiment, the electrodes or needles 25 tend to be energized in smallgroups, and sequentially from one end of the jaw 21 to the other end ofthe jaw 21. In a similar embodiment illustrated in FIG. 25, theenergizing block 67 is carried by a pusher 69 having an inclined plane70. This plane 70 lifts the needles 25 from a withdrawn position to anexposed operative position, at which point the block 67 sequentiallyenergizes the electrodes or needles 25.

Looking now to FIGS. 26 and 27, a method of providing continuous contactbetween the penetrating needles 25 of the first jaw 21 and the contactsurface of the second jaw 23 is shown where the second jaw 23 comprisesa “honey-combed” structure 72. This structure allows the penetratingneedles to enter into the second jaw portion without compressiveresistance. As the second jaw 23 is compressed upon tissue, thehoneycombed structure 72 is drawn or pushed axially, as shown by anarrow 74 in FIG. 27, so that the penetrating needles are forced intoelectrical contact with the second jaw 23.

FIGS. 28-30 illustrate schematically the effect which electrosurgeryand/or heat has on the compressed tissue 18. The application of highfrequency electrosurgical waveforms 76 will vaporize the fluid withinthe cells of compressed tissue and cause them to literally explode. Ablended signal that includes an overwritten waveform, will providehemostasis or coagulation as the cutting occurs. In addition to thecutting and coagulation, heat, whether generated indirectly byelectrosurgical current flow or directly by heating of an element, tendsto dry the tissue and denatures the cellular structures. In the presentcontext, this heat produces a denatured column which defines thecontinuous lumen 41 through the tissue 18.

With reference to FIGS. 31-34, a hemostatic clamp 76 is shown configuredgenerally as a scissors-like device. The opposed tissue contactingsurfaces are configured with tissue penetrating needle members 25, 61adapted to penetrate interposed tissue. An electrosurgical instrument,either monopolar 78 (FIG. 34) or bipolar 81 (FIG. 33, may be used tocontact the hemostatic clamp 76 and deliver current flow through it. Adirect heat source 83 (FIG. 32) or an external source 85 could also beused. Discharge of this energy creates heat in the small diameterneedles 25, 61 where the current density is elevated.

A close look at FIG. 35 reveals that a further embodiment may include aplurality of tissue penetrating needles 25 that are urged into andthrough tissue to be adhered. The needles 25 are configured to allow asmall flow of blood into the puncture sites. The blood coagulates andforms a glue-like substance when mixed with other chemical componentsintroduced to the site for example by a disposable chemical releasingsleeve 87. The jaw 23 can be covered by the sleeve 87 to provideincreased continuity with the jaw 23 and the tissue 18.

Standard electrical schematics are seen in FIG. 36 where it is shownthat an ES generator “monopolar” circuit 90 comprises an activeelectrode 96 and a passive electrode or “grounding-pad” 52. The currentdensity at the active electrode 96 contact site is substantially greaterthan the current density at the attachment site of the passiveelectrode. For example, in a typical arrangement, the current density ofthe active electrode contact area might be two thousand times greaterthan the current density at the passive electrode site. The elevatedcurrent density relationship produces a spark at the site of contact ornear contact of the active electrode 96 with the tissue 18. However, thereturn path of the current flow is dissipated, dispersed or diluted dueto the larger surface area of the return electrode or grounding pad 52.

The bipolar arrangement, shown schematically in FIG. 37, provides anelectrical potential between two nearly identical active electrodes 92,94. The current density associated with the two electrodes 92, 94 isnearly the same. Tissue may be grasped, for instance between the twobipolar electrodes 92, 94, and cut and coagulated without the patientbeing a part of the electrical circuit as is the case with monopolarelectrosurgery.

A hybrid form of electrosurgery is illustrated in FIG. 38 where anactive electrode 96 is positioned adjacent to a return electrode path 98upon a single instrument. To illustrate, an instrument having a metalshaft and an insulated metal electrode works by providing high currentdensity at the active electrode 96 and less current density on thereturn path 98.

A more simple approach, illustrated schematically in FIG. 39, involvesuse of direct current (D-C) such as that derived from a battery orrectifier 101. This D-C apparatus supplies one pole to one electrodemembers 103 and the opposite pole to the opposite electrode member 105.Needles 107, in the form of resistive electrode members communicatebetween the poles and generate heat.

It will be understood that many other modifications can be made to thevarious disclosed embodiments without departing from the spirit andscope of the concept. For example, various sizes of the surgical deviceare contemplated as well as various types of constructions andmaterials. It will also be apparent that many modifications can be madeto the configuration of parts as well as their interaction. For thesereasons, the above description should not be construed as limiting theinvention, but should be interpreted as merely exemplary of theembodiments. Those skilled in the art will envision other modificationswithin the scope and spirit of the present invention as defined by thefollowing claims.

1. A tissue welding apparatus for fusing a first piece of tissue to asecond piece of tissue disposed in a surface proximate relationship tothe first piece of tissue, comprising: an elongate shaft; a first jawcarried by the shaft; a second jaw carried by the shaft in an opposingrelationship with the first jaw; a plurality of needles extending fromand carried by the first jaw and adapted to move with the first jaw andrelative to the second jaw into the first piece of tissue and the secondpiece of tissue to create a channel defined by the first piece of tissueand the second piece of tissue; and an energizing block movablelongitudinally along the first jaw electrically coupling a subset of theplurality of needles to a source of heat, the heat source havingproperties for heating the plurality of needles and for denaturing thetissue defining the channel.
 2. The apparatus recited in claim 1,wherein the second jaw has a fixed relationship with the shaft; and thefirst jaw has a movable relationship with the shaft and the second jaw.3. The apparatus recited in claim 1, wherein the source of heatcomprises an electrosurgical generator.
 4. The apparatus recited inclaim 3, wherein at least the first jaw comprises an electrosurgicalmonopolar electrode.
 5. The apparatus recited in claim 3, wherein thefirst jaw and the second jaw comprise electrosurgical bipolarelectrodes.
 6. The apparatus recited in claim 1, wherein the source ofheat comprises a direct current electrical power source. 7-31.(canceled)
 31. The apparatus recited in claim 1, wherein the second jawcomprises a continuous flat planar surface along an entire length of thesecond jaw facing the first jaw.
 32. The apparatus recited in claim 1,wherein each of the plurality of needles comprise an electrosurgicalelectrode.
 33. The apparatus recited in claim 1, wherein the second jawcomprises an electrosurgical electrode.
 34. The apparatus recited inclaim 1, wherein the source of heat comprises a solid state energysource and wherein each of the plurality of needles is an individualelectrode selectable to receive electrical energy from the solid stateenergy source.
 35. The apparatus recited in claim 1, further comprisinga removable sleeve covering the second jaw.
 36. The apparatus recited inclaim 1, wherein the second jaw comprises a plurality of aperturesfacing the plurality of needles on the opposing first jaw.
 37. Theapparatus recited in claim 35, wherein the second jaw is movable in afirst direction towards the first jaw positioning each of the pluralityof needles into an associated aperture of the plurality of apertures ofthe second jaw.
 38. The apparatus recited in claim 36, wherein thesecond jaw is movable along a second direction being different from thefirst direction, each of the plurality of needles inserted into theassociate aperture of the plurality of apertures contacting portions ofeach of the plurality of apertures of the second jaw.
 39. The apparatusrecited in claim 1, wherein the energizing block sequentially supplyingelectrical energy to groups of the plurality of needles along the firstjaw.
 40. A tissue welding apparatus for fusing a first piece of tissueto a second piece of tissue disposed in a surface proximate relationshipto the first piece of tissue, comprising: an elongate shaft; a first jawcarried by the shaft; a second jaw carried by the shaft in an opposingrelationship with the first jaw; a plurality of needles extending fromand carried by the first jaw and adapted to move with the first jaw andrelative to the second jaw to the first piece of tissue and the secondpiece of tissue; and an energizing block movable from a proximalposition to a distal position and sequentially supplying electricalenergy to groups of the plurality of needles along the first jaw. 41.The apparatus recited in claim 40, wherein each of the plurality ofneedles comprise an electrosurgical electrode.
 42. The apparatus recitedin claim 40, wherein the second jaw comprises an electrosurgicalelectrode.
 43. The apparatus recited in claim 40, wherein the source ofheat comprises a solid state energy source and wherein each of theplurality of needles is an individual electrode selectable to receiveelectrical energy from the solid state energy source.
 44. The apparatusrecited in claim 40, wherein the second jaw comprises a plurality ofapertures facing the plurality of needles on the opposing first jaw, thesecond jaw is movable in a first direction towards the first jawpositioning each of the plurality of needles into an associated apertureof the plurality of apertures of the second jaw.